Gas turbine engine blades

ABSTRACT

A gas turbine blade has a hollow interior space in which is disposed a double-walled insert. The insert forms chambers with the blade walls, and together with the interior of the insert these chambers form part of a path for the flow of cooling fluid through the blade. The chambers provide separated in-flow and out-flow chamber(s), arranged so that cooling fluid supplied from one end of the blade passes through the in-flow chambers to the interior of the insert at the leading edge of the blade, and from there passes to the trailing edge of the blade where it leaves the blade by way of the out-flow chamber(s).

[ Jan. 1, 1974 3,560,107 2/1971 Helms..t.............. 3,635,587 l/l972Giesmanetal...

[ GAS TURBINE ENGINE BLADES [75] Inventor: Alan Moore, Bristol, England[73] Assignee: Rolls-Royce (1971) Limited, Primary Examiner-Everette A.Powell, Jr.

London, England Attorney-Richard K. Stevens et a1. 1

Aug. 22, 1972 Appl. No.: 282,779

ABSTRACT [22] Filed:

A gas turbine blade has a hollow interior space in which is disposed adouble-walled insert. The insert forms chambers with the blade walls,and together with the interior of the insert these chambers form part ofa path for the flow of cooling fluid through the blade. The chambersprovide separated in-flow and [52] US. [51] Int. [58] Field ofSearch..................

out-flow chamber(s), arranged so that cooling fluid S T N w 3 g e my 8 DE n N U supplied from one end of the blade passes through the in-flowchambers to the interior of the insert at the leading edge of the blade,and from there passes to the trailing edge of the blade where it leavesthe blade by way of the out-flow chamber(s).

66 ma 66% ii 446 Meyer et al...... Banthin et a1. Kercher 10 Claims, 2Drawing Figures GAS TURBINE ENGINE BLADES This invention relates to theblading of gas turbine engines, and although not so restricted, hasparticular reference to rotor blades for such engines.

As is known, it is advantageous to provide for the cooling of gasturbine engine blades, and many different ways of doing this are known.In particular, it is known to provide a cooling air flow through theinterior of the blade, and the cooling is the more effective, thegreater the volume of air flow and the greater the velocity of the airas it passes through the blade.

In very small rotor blades, e.g., less than 1 Va inch long considerabledifficulties are encountered in providing flow channels by means ofwhich satisfactory cooling can be achieved. The present invention aimsto provide a rotor to stator blade construction which enables improvedcooling to be obtained.

Accordingly the invention provides a gas-turbine blade with a hollowinterior space divided into in-flow and outflow chambers for coolingfluid, having a doubled-walled insert of which the interior communicateswith the in-flow chambers in the region of the leading edge of theinsert and communicates with the out-flow chamber(s) in the region ofthe trailing edge thereof, the in-flow chambers lying on both sides ofthe insert and being arranged for supply with cooling fluid at one endof the blade.

In a preferred form, the invention is applied to rotor blades which arefed from the root end.

The invention will now be described with reference to theaccompanying'drawing, in which:

FIG. 1 shows a sectional elevation of a gas-turbine rotor bladeaccording to the invention, the section being taken on the line B--B inFIG. 2; and

FIG. 2 shows a section on the line AA in FIG. 1 to a scale times asgreat.

The turbine blade has leading and trailing edges 10,

11 a shroud end 12 and a root end 13. The bladeis hollow and the spacewithin it is divided into air flow chambers for cooling air.

A double-walled insert 14 is mounted within the blade, being brazed tothe blade at its root end but otherwise unattached to allow fordifferential expansion. The insert divides the interior of the bladeeffectively into two spaces lyingeither side of it which spaces are thensubdivided by a fin 15 cast on the interior surfaces of each of thewalls 17, 18 of the blade. The insert 14 is located within the blade bythese fins l5, and also by a large number of pimples 16 indicated inFIG. 1 by crosses. Towards the trailing edge 11 of the blade, at pointsto which the insert 14 does not extend, the blade is strengthened bypedestals 19 which extend fully between the walls 17, 18 of the bladeand which are also indicated in FIG. 1 by crosses. The particular bladeconstruction shown has an additional advantage in that the fins l5,pimples 16 and pedesdals 19 can all be cast with the blades, using asingle piece core, which facilitates production of the blades.

The two walls on the insert 14 are held spaced apart by spacers 21. Theleading edge 22 of the insert is open along its length, while thetrailing edge has a series of apertures 23. The insert is narrower atthe shroud end than at the root end, and the fins 15 which support itare correspondingly curved. The leading edge of the blade has leadingedge film cooling holes 24 and slots 25 are provided in the trailingedge.

In operation, a cooling air flow enters the blade at the root end 13 andpasses into air inflow chambers 26 lying both sides of the insert overthe full radial length of the blade. The cross section of the inflowchambers 26 diminishes towards the .shroud end 12 to allow for thereduction in volume of airflow due to the cooling holes 24, and the flowof air which passes into the open leading edge of the insert 14. Airwhich passes into the interior of the insert flows chordwise from theleading edge towards the trailing edge and emerges through the apertures23 into an air outflow chamber 27, and from there the air escapesthrough the slots 25.

A certain amount of impingement cooling also takes place at the leadingedge of the blade as the cooling air enters the passage 20 in theleading edge from the spaces between the first row of pimples 16.

With this arrangement, the initial air flow is spanwise of the blade,and because of the small cross-sectional area between the insert and theblade wall, the air flow speed is substantially increased and the air atits coolest comes into direct contact with the parts of the blade to becooled. Air entering this insert flows chordwise through a greatercross-sectional area and reaches the trailing edge with little pressureloss through the insert.

Although pimples 18 of any desired shape may be used for the location ofthe insert, diagonal fins could be used in addition, or in their place,which would also serve to guide cooling airfrom the root end toward theshroud end of the blade.

Amongst other possible variations of the described arrangement are: theapertures 24 are omitted; the apertures 25 are omitted and the coolingair is arranged to leave the blade at the srhoud end; a liquid or a gasother than air is used for cooling; the pimples 16 and/or fins 15 areother than integrally formed on the inside surfaces of the blade walls;the apertures 23 are replaced by a continuous slot along the trailingedge of the insert, and, conversely the leading edge of the insert isclosed and apertures analogous to the apertures 23 are provided in thewalls of the insert on either side of its leading edge.

Another possible variation of the described arrangement is the provisionof one or more bleed holes in the fins 15 to allow a small amount of airat the root end of the blade to pass to the outflow chamber 27 directly,that is to say, without passing through the insert 14.

What is claimed is:

l. A gas turbine blade having opposed walls defining therebetween ahollow interior space, a double-walled insert within said space, andmeans defining two inflow chambers between said insert and said walls,one on each sideof the insert, and at least one out-flow chamber, theinsert interior communicating with the in-flow chambers in the region ofthe leading edge of the insert and communicating with said out-flowchamber in the region of the trailing edge thereof, the in-flow chambersbeing arranged for supply with cooling fluid at one end of the blade. I

2. A blade as claimed in claim 1, where the in-flow and out-flowchambers are separated from one another by fins integrally formed on theinterior surfaces of the blade walls and abutting the insert on eitherside thereof.

3. A blade as claimed in claim 1 wherein location for the insert withinthe blade is provided by a plurality of projections integrally formed onthe interior surfaces of each blade wall and abutting the insert oneither side thereof.

4. A blade as claimed in claim 3, wherein at least some of theprojections are in the form of fins arranged to guide cooling fluid fromthe said one end of the blade towards the other end thereof.

5. A blade as claimed in claim 1, wherein the interior of the insertcommunicates along the leading edge of the insert with a chamber commonto the in-flow chambers and separating the leading edges of the bladeand the insert, the walls of the insert being maintained in spacedrelation by the plurality of spacers.

6. A blade as claimed in claim 1, wherein a plurality of apertures areformed in the region of the leading edge of the blade for allowingcooling fluid to pass to the exterior of the blade from the inflowchambers.

7. A blade as claimed in claim 1, wherein a plurality of apertures areformed in the region of the trailing edge of the blade for allowingcooling fluid to pass to the exterior of the blade from the out-flowchamber(s).

8. A gas turbine rotor having a plurality of blades as claimed in claim1 arranged for supply with cooling fluid at their root ends.

9. A blade as claimed in claim 1, which includes one or more bleed holesconnecting the inflow chambers and the outflow chamber(s) directlytogether at the said one end of the blade.

10. A blade as claimed in claim 1, wherein the insert is mounted withinthe blade by brazing at one end thereof, being otherwise unattached toallow for differential expansion.

1. A gas turbine blade having opposed walls defining therebetween ahollow interior space, a double-walled insert within said space, andmeans defining two inflow chambers between said insert and said walls,one on each side of the insert, and at least one out-flow chamber, theinsert interior communicating with the in-flow chambers in the region ofthe leading edge of the insert and communicating with said out-flowchamber in the region of the trailing edge thereof, the in-flow chambersbeing arranged for supply with cooling fluid at one end of the blade. 2.A blade as claimed in claim 1, where the in-flow and out-flow chambersare separated from one another by fins integrally formed on the interiorsurfaces of the blade walls and abutting the insert on either sidethereof.
 3. A blade as claimed in claim 1 wherein location for theinsert within the blade is provided by a plurality of projectionsintegrally forMed on the interior surfaces of each blade wall andabutting the insert on either side thereof.
 4. A blade as claimed inclaim 3, wherein at least some of the projections are in the form offins arranged to guide cooling fluid from the said one end of the bladetowards the other end thereof.
 5. A blade as claimed in claim 1, whereinthe interior of the insert communicates along the leading edge of theinsert with a chamber common to the in-flow chambers and separating theleading edges of the blade and the insert, the walls of the insert beingmaintained in spaced relation by the plurality of spacers.
 6. A blade asclaimed in claim 1, wherein a plurality of apertures are formed in theregion of the leading edge of the blade for allowing cooling fluid topass to the exterior of the blade from the inflow chambers.
 7. A bladeas claimed in claim 1, wherein a plurality of apertures are formed inthe region of the trailing edge of the blade for allowing cooling fluidto pass to the exterior of the blade from the out-flow chamber(s).
 8. Agas turbine rotor having a plurality of blades as claimed in claim 1arranged for supply with cooling fluid at their root ends.
 9. A blade asclaimed in claim 1, which includes one or more bleed holes connectingthe inflow chambers and the outflow chamber(s) directly together at thesaid one end of the blade.
 10. A blade as claimed in claim 1, whereinthe insert is mounted within the blade by brazing at one end thereof,being otherwise unattached to allow for differential expansion.